In announcing the mileage proposal, the administration said the freeze would save 1,000 lives a year. But in a June email, the EPA told the Department of Transportation that it would slightly increase highway deaths.

EPA spokesman John Konkus says the new documents made public Tuesday were just a small part of administration discussions on the mileage proposals.

The Trump administration has proposed freezing mileage standards after 2020. The tougher Obama-era mileage rules were meant to reduce pollution and climate-changing emissions.